3. Earth-Sheltered
It turns out hobbits had the right idea. Earth-sheltered homes, such as the underground dwelling of Bilbo Baggins in "The Hobbit," are energy efficient, soundproof and fire-resistant. They can also be built above ground, with the sides of the home or the roof covered with earth. Underground earth-shelters aren't completely dark; windows and openings provide heat and natural light.
Water drainage systems must be designed to channel the water away from the structure, and it's best to build earth-sheltered homes in soils that are permeable, which allows the water to drain, as opposed to a cohesive soil like clay, which will expand with the water [source: U.S. Department of Energy]. Soils also should be tested for their load-bearing capabilities. The construction materials for building the inside can be natural, including earthbag, rock, local wood or straw. An earthship is a type of earth-sheltered home.
